1. Field of the Invention
The present invention is related to an improved structure of a multi-frequency antenna for a mobile phone, and especially to an antenna of which the novel designs of a coil and its related electric connecting elements make the antenna suit mobile phones of various frequencies under the situation of convenient manufacturing and assembling.
2. Description of the Prior Art
Antennae for mobile phones using only a single frequency (e.g. 900 MHZ) can suit two different frequencies (900 MHZ and 1800 MHZ) when it uses a frequency matching structure. While the antennas for mobile phones available presently sometimes use even higher frequencies, such as 1850 MHZ-1990 MHZ.
In such two-frequency antennas, generally coils of different diameters are used for matching, or metallic conductive pieces of in the shape of waveforms are used in lieu of coils, such as those shown in FIGS. 1 and 2. The metallic conductive piece 10 therein is pressing formed from thin metallic sheet, and includes generally a lateral vertical waveform section 11 and a horizontal waveform section 12. The metallic conductive piece 10 is a plane conductor with a specific width when it is pressing formed (as shown in FIG. 2), it can then be wrapped around the outer peripheral surface 14 of a post 13 of an antenna.
By virtue that the mutual contiguous lateral vertical waveform section 11 and horizontal waveform section 12 have to be used, the conventional two-frequency antenna structure is made from thin metallic sheet, thereby, precision die is required to pressing forming the whole metallic conductive piece, and this results higher cost. And the plane metallic thin sheet has to be wrapped around the post in processing; it is bothersome for manufacturing. And more, using of such a two-frequency antenna with large changing, the original production procedure must be changed, a new die has to be opened, working hour for manufacturing and assembling is increased, thereby, cost of production must be largely increased.
The object of the present invention is to provide a multi-frequency antenna for a mobile phone, and especially to a multi-frequency antenna rendering manufacturing and assembling thereof faster and more convenient for largely reducing cost of production must.
To get the above stated object, the present invention is provided with a coil which is dense and also sparse, the coil is positioned between the inner top surface of an outer sleeve and a receiving seat to form an electric conducting system for signal receiving and emitting of the antenna in cooperation with a contact piece. In the longitudinal length of the whole coil, spacing between every two rings of the coil is smaller, this is the dense section of the coil, while the remaining part is the sparse section; in this mode, the coil can be a multi-frequency sensing member after it is assembled.
The abovementioned dense section and sparse section have a ratio of length 1:2, the ratio of the spacing of their rings is 1:3.
The dense and sparse coil can be placed in the hollow interior of an inner insulation sleeve of the antenna, the bottom most ring of the coil is mounted in a metallic receiving seat in a bottom hole of the inner insulation sleeve, the topmost ring thereof is abutted against the inner top surface of the outer sleeve slipping over the inner insulation sleeve. In cooperation with an elastic contact piece mounted on the bottom of the inner insulation sleeve, the coil can be assembled in a mobile phone and used as the signal receiving and emitting antenna device.
The present invention will be apparent in its novelty and other characteristics after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings.